Author:

John Rice(MIT PSFC)

Changes in the core toroidal rotation velocity profiles following injection
of lower hybrid (LH) waves have been
documented in Alcator C-Mod plasmas. Shot by shot scans of LH input power
have been performed at fixed magnetic field and electron density for several
plasma currents. If the input power is low enough that there are still
sawtooth oscillations, the change in the core rotation is in the
counter-current direction, consistent in sign and magnitude with direct
momentum input from the LH waves. If the power level is high enough that
there are significant changes to the q profile, the change in the toroidal
rotation is in the co-current direction, consistent with changes in the
residual stress through its dependence on the current density profile. The
direction of the rotation changes depends on the whether q$_{\mathrm{0}}$ is
below or above unity, and seemingly not on the magnetic shear.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2015.DPP.PI3.2